(CNN) --Satellites, pagers, cell phones, and electrical grids could be affected Friday by a moderately powerful ejection of magnetic material from the sun.

Space weather forecasters say the coronal mass ejection, or CME, was detected Wednesday morning at 3 a.m. EDT. It is expected to reach Earth about 3 p.m. EDT Friday, and its effects could last 12 to 18 hours.

Space weather forecasters at NOAA's Space Environment Center in Boulder, Colorado, warn a number of industries when there is a major release of the hot flares of solar gases. They usually take two to four days to reach Earth.

In the midst of these electromagnetic events, power companies often refrain from peak uploading and downloading of power across the grid. Airlines are also alerted, because some navigation systems may be affected.

Satellites are perhaps most affected by the solar activity.

"Satellites live and breathe in space; they are very vulnerable to solar activity," said Larry Combs, NOAA space weather forecaster. "They affect our banking systems, our TVs and cell phones, all the luxuries of life."

Combs said some operators will put their satellites into a stow, or a sort of "sleep" mode during the highest impact of the electromagnetic activity.

In the past there have been major outages and interruptions of cell phone and pager service because of electromagnetic interference.

"Sometimes satellites can be damaged beyond repair," said Combs. But there are hundreds of satellites in space now, most with some sort of backup possible.

The CMEs can also have a biological effect on humans, so space forecasters do daily briefings that might affect any crews in space. For example, it would not be a good idea to do a space walk when a solar event is predicted.

Forecasters track the CMEs from the time they leave the sun, and as the material gets closer to earth they pick up increases in X-rays and electromagnetic emissions.

Solar activity is rated, similar to the system for hurricanes or earthquakes, on a scale of one to five, with 5 as the most intense. Friday's activity is expected to be a 3, or moderate.

These magnetic storms can also produce spectacular displays of the northern lights; NASA's Space Weather Web site is predicting that the northern lights could be visible as far south as Oregon and Illinois.

Scientists made their first solar flare forecasts back in 1964. Since then a variety of instruments, both in space and on the ground, have improved their ability to track the activity.

"But like anything in nature, sometimes they don't act like we expect them to," Combs said.